Mercruiser 140 camshaft gear messing up or grinding with the distributor drive gear?

Question

this is the second distributor that i went through. it is for my mercruiser 140 4 cyl. 1 st problem was the distributor drive gear got chew up so bad it wont turn the rotor. 2nd same thing but notice it before it got really mess up. so was wondering what could have cause it? bad cam bearing? or the camshaft itself gears on the cam doesnt look to mess up but its still in the engin

Answer 1

If your engine is late 1990's MC140  this is a very unusual problem.  The engine is unique to Mercruiser.  If the distributor failed, I'll bet that this engine has been "rebuilt" or other service done because of problems with the exhaust manifold.  Bottom line is that you need to have it checked by an "engine" man.  It sounds like the camshaft is not properly aligned.   My memory is that there is a long shaft that drives the oil pump, that is a part of this distributor.  Secondly this dist. is "non-automotive"  and I've only replaced one in 20 years, and that was because of a bearing failure.

Answer 2

Hmmm? sounds like you are getting a lot of endplay in the cam the cam has a plate behind the timing gear held in with two screws (thrust plate) if it backed the screws off could let the cam "walk" back an forth wearing the dist gear teeth one easy to check is to try and push the cam gear forward and back with the dist out of its hole in the block take a screwdriver and "CAREFULLY" push  the cam gear torwards the rear and then towards the front sould only feel a few thousands of an inch clearance but if it moves quite a bit you need to pull front timing cover and investigate why  hope i helped you also check oil pump drive for binding good luck